Mechanical governor



July 26, 1949. J. TREVITT' I MECHANI C AL GOVERNOR 2 Sheets- Sheet 2 Filed Oct. 24, 1945 l 74 5i H Tag. 5'. Direction of movemem'r Direc'aion of movement Axis f rotation.

' INVENTOR.

John H. fi'eviiz RNEYS Patented July 26 1949 STATES PATENT G F I C'E GGWERNQR J ohnv .H. .Trevitt, Bridgeport, Goran, assignor 4:0

Dictaphone .Gorporation, New York, N. 35., a xcor giora'fion of New York --iflapplication @etober 24, 1945Se1iial No. $243212 invention relates :to centrifiugal governors and, more particularly, .governors suitable :for controllingv the speed (of phonograph motors and the .ilike, wherein ;a controlled brahingaction is employed to regulate a iwideevariationtof the speed.

In :the oase of v recomiing phonogtfimhic imamaintenance of constant necessary ztoipnevent distortima and-,changeaif :pitch in the recorded-sound. These reasons for holding the speediconstant are also applicable :to reproduoingsmachines; abnt,..in addition, zit is necessary toivarytthespeemover azpmdetermlned rangerand the-selected ,speed :constant.

"fine to'hject of thepresent :invention is-t 311lovide a simple and eificient :governor ofismal-lisize having zgood megulaticn. zandrsuibstantially vibrationless operation nver:thewholecontrolledspeed ramge hf the governor.

Another object is to iprovide a simple and practical governor of the above type adapted to control a speed variation of new \widerange.

' w ther-objects will *be in apart obvious and pant ipointed :eut hereinatter.

The invention, 3.0COI'diIlg1y,rDn5iSbS in.-the-:iea-. times -oi construction, acombination :of elements, and arrangements of parts which will be-exemplie fled in the Stl'llCtllIB'diO the hereinafter described andthe scope of .the application of which will be.

inflicatedinthe following claims.

In the accompanying drawings, in which is shown one ofthe 'various'possible embodiments of theinvention,

Fig. '1 is aniendslevation showing themotor whose speed is 'tobe controlled, with'the governor mounted in front thereof upon themotor shaft;

"Fig. 2 is a side elevation, partly broken away, asseen from the leftiimEig. 1;

Fig.8 is a top .plan 'view .ofsthe apparatus as shown .-in Fig, 41 with weights shown a in zOIOSfld positionxnearlthe-shaftaxis;

Fig. 4 is a vertical cross-sectienof itheigovernor parts taken on line 44 of Fig. 1;

Fig. 5 is radiagram showing (the distribution of forces in a governor having swinging weights withthegpivotim the-.asiis 20f therrntatingzshait;

:Eig. 6 J is .12. :similar diagram ;in a. governor :cf the same type having sthesweights acennenteddiy-a tension..-spring ;and cams AfOI icounteizacting-fthe forces which :are due simply lto action ,icfsthe weights; and

-Eig. .7 $3.43,. diagram similar to 6 showing weights and cams in axliiferent tcnerativeipcsi tion.

:In t8, :patent rapplicatiomof Boss- I2 meyen filed September 21,;1945, SeriaL NQBI'UYBZ, now Rat. No. 2 4333385, there was shown a ;governoracomprising weights ,ypivotally mounted .to swing about axes in andtnormal to; the motor shafit,'whicl1 wereaotuated centritugally to cause axial :eooperation oithe brake-members of the governor, thuslefiezcting friction-a1 control of the speed of the motor. In that disclosure no spli n s were employed to rmodify ithe :thrust effect of the weights, but the weights themselves were (designedicoact (as tcamss-tocause limited modification 'of :theefiectsofichanging centrifugal action. Thismedifying :means as embodied in the cams of :the generahshapeshowndn thesaid epplication, whilersatisfactoryiorthelpurpose where arelatively range of speed variation .is Wanted, ifailsin .a situation where-speeds .to. be controlled :may vary all rthe way from \a lcwof about ,=R.. P. 5M. to-whigh of :2800 R..M,,-,a four to zcne speed wariation. .The- :difiioulty -.of covering .such :a wide range .-is augmented Icy-the requirementnof good speed regulation throughout the orange. Since, for use in wide range phono raph control, the :motor rhasdto be simple in construction and small/in :size Pin -.order to secure controlled "wide speed waniation with changesof mechanical load causediby the'raction of :a governor. zit is;,-necessary rte-me either (a series commutator :motcrlor ran induce tion motor having highrotor resistance. Both-of these-motor types have much zhighertorque at low thamat high speeds.

ZI he govern-or herein described meetssatisiactorilyrallroirthe conditions above setliorth. it is of the centrifugal weight operated {type having springs to counteract the ccentriiugal action. Weight operated sgovernors ,=exert .a (force which increases with the square of:the motor speed, While the speed-torque characteristic of the motor requires :a small doses atl-highvspeedeand a large braking iorcaat-low. Herein Lthis reversal of the .forceespeed gradient of the weightslis-obtained principallwby \the j ise o i \counteracting springs, but also, to some degree, .as :invthe :said Bcssmeyer application, byea change (of -.direction of the actingforces hy meansoi-icamswhichshitt the ipoint of (attack -.of :the ltransmitted ;braking force .tfrom appoint .of l rgest mechanical iamplification at lowest speed to :8, point of greatest mechanical reduction (at highest speed.

:Reterring :tothe-drawinj-gs, the imotorpindicatcd at I .i-sof the capacitor (min iinductive type with two poles andwithlhigh :resistance :sguirrel cage rotor. I heicontmlled ispeediis between'flilfllzanfi 280MB. 1P. mhe imotorshaitiz carries :a LCD? 3 axial shaft extension 3 having a sleeve portion 4 fixedly mounted upon the end of shaft 2 by means of set screws 5 (see Fig. 4).

Each of two governor weights 6, see Figs. 1 and 3, is mounted by cam plates 1, loosely supported upon a cross-shaft or pivot 8 extending through a bore 9 in the shaft extension 3. The two shafts interfit tightly and their axes intersect at right angles. The pairs of cam members 1 comprising part of and supporting the respective weights are slightly offset upon the cross-shaft 8 relative to the axis of the shaft extension 3, best shown in Fig. 1, so that in operation the inner cam plates, one of each pair, are pressed by a small component of centrifugal force against opposing flattened sides IQ of the shaft extension 3. This prevents binding between the adjacent members of the two sets of cam plates. Each weight proper 6 is made up of three sections 6a, 3b and 60 mounted upon a stud II, and the cam plates are mounted upon the stud I I between the central weight section 6b and the outer sections 6a and 6c. The studs are threaded to receive nuts l2 for holding the parts together. Extensions of the studs H are grooved to receive the looped ends of a pair of tension springs 13 which tend to hold the weights inwardly against the motor shaft extension 3.

By reference to Fig. 4, it will be seen that the contiguous cam plates on either side of the shaft extension are held more or less loosely against the said flattened portions ill by means of nut studs M which engage threaded portions l5 of the cross-shaft 8 and are drawn tightly against shoulders l6 formed upon the cross-shaft, the cam plates being held rotatably upon the cross-shaft between the opposing surfaces of the stud nuts and extension shaft. Thus the cams are held in position upon the cross-shaft with sufficient operational tolerance by the nut studs. The outwardly extendings ends of the nut studs serve as bearings for small rollers I! which are held thereon by washers l8 and screws I9 which take into threaded holes in the ends of the nut studs.

A brake disc 20 having a hub portion 2| is rotatably and slidably mounted upon the shaft extension 3 between the cross-shaft 8 and the sleeve 4. A compression spring 22 interposed between sleeve 4 and hub 2|, serves at all times to press the brake disc resiliently against the functional faces 23 of the cam plates. Rotation of the cams with the shaft extension 3 is transmitted to the brake disc 20 by means of pins 26', carried by the brake disc in the path of rotation of the rollers I? about the shaft 3.

The control mechanism for the governor comprises a control disc 24 carrying three equally spaced brake shoes 25 adapted to cooperate with the brake disc 26 to control the speed of rotation of the motor shaft and to vary at will the speed at which the governor is to control.

Referring to Figs. 1, 2 and 3, the control disc 24 is supported by a pair of bracket members 26 whose rearward extensions are pivotally mounted upon a bifurcated lever 21 by means of pivot screws 28. The lower ends of said lever are pivotally mounted upon a motor frame bracket 29 as by pivot bolt 30, so as to enable a rocking movement of the lever and control disc toward and away from the governor brake disc 20. An upper motor frame bracket 3| supports a slide plate 32 which is provided with elongated slots 33 through which extend shoulder screws 34 which are threaded into the bracket 3 i. The right-hand end of plate 32 carries a downwardly extending flange 35 which is also slotted, as at 36. A bolt 31 pass ing mutually through slot 36 to a point near the upper end of lever 21, secures said lever acfiustably to said slide plate. Bracket 3| also supports in well known manner, as at 38, the outer elements of a Bowden wire control member. An upstanding contact member 39 carried by the plate 32 is held resiliently against the end of the inner element of the Bowden wire (as at 43) by means of a tension spring 4|, stretched between a pin 42, upstanding from the bracket 3!, and a pin 43 extending laterally from the side of the lever 31, at its upper end.

From the foregoing description of the governor control mechanism it will be obvious that any desired position may be given to the control disc 24 with respect to the brake disc 26 so as to determine the controlled speed of the motor shaft by simple manipulation of the Bowden wire from any suitable remote point. Thus the axial operative position of brake disc 261s determined by the setting of the governor control mechanism.

Normally when the motor is not in operation the weights 6 are held against the shaft extension 3 by the pressure of spring 22 upon the brake disc, in which position little or no pressure exists betwee the brake disc and the brake shoes 25. When the motor starts to rotate, the weights move outwards pressing disc 26 against the brake shoes. The braking torque is determined by the angle of the weights and the contact or operating point of the cam surfaces, which is itself determined by the setting of the governor control.

The force equations in the new governor may. best be understood by reference to the'diagrammatic figures of the drawing, 5, 6 and 7.

Fig. 5 shows the principle involved in the suspension of the governor weight.

The weight with mass m is forced to rotate with the angular velocity w of the motor shaft and is pivoted for swinging in a radial plane with a radius 11, the distance between pivot center and center of gravity of weight. The anglebetween the motor shaft and the common center line of the weight and pivot is a.

The centrifugal force C acting on the weight m is then:

C=mw ri sin a (1) The torque Mm around the pivot exerted by C is:

The axial braking force P exerted on the brake disc for any angle a and speed 20 is:

T2 w T2 SlIl 2a (3) where m is the radial distance from the pivot to the point of attack of the force P. This force P is largest for sin 2a=1 or a=45 and it is zero for a=. The variation of the braking force dP for any change dw is:

2 (IP: 2a=dP= mind ng; sin 2a gamma The ount rac in force ti the ring, s -'s=KrI (sine-smile) I ('5) hilt-3'sis the Spring constant-and A0, is th angle corresponding to 'no tension on the spring.

The torque Ms around a pivot exerted by the spring force s is:

Ms=Sr1 cos a (6) Combining 2 and 6 gives the torque M for one weight with counteracting spring force S as:

M=Mm-Ms=%w 'r sin 2iz-Sr cos a (7) The brake force F for one weight is now:

where a e now varies according to the cam shape. The regulating force is, as before:

w r sin 2a-S cos a) as the spring force does not change with a mere change of speed in a rigid system. But sin 2a will be now much larger than before as the travel of the weights has been reduced.

The brake torque T exerted on the motor depends on the coefiicient of friction 1 between brake shoe and brake disc, on the radius 13 of the brake shoes and on the number of weights N and the brake force P T12 dP=m w dwsin 2a T=fPNr =f (m'w 1' sin 2a-2s cos a) (9) for two weights.

The gain in regulating force dP by introduction of the springs as in the present embodiment can be shown as follows:

A certain brake force is required to hold the motor speed down to a desired amount for the system shown in Fig. 5. This brake force is not changed by the changes .indicated in Fig. 6 as the motor and brake disc were not changed. The brake force for system 2 can be expressed as P=(n+l)P-nP where (n+1) P stands for and WP stands for the spring force is cos a The angle a for the same P as in system 1 is, of course, different from the angle a in system 1. dPz for system 2 is then, by comparing 4 and 10,

(1P2: (n+1) dPi From the above it will be easily understood in system the reguiationiwill .befbettertflr larger the spring force as:

48in, i fpj i j When'the spring force is, for'instaneatenthebrake force P; then the regulating force will beeleverr times the regulating --force withoutitwillbe seen from the-above that there is provided by this invention a constructi'on of an: essentially practical nature inwhichthe several objects of invention are attained.

many possible embodiments may be made at the invention without departing-1mm the scopethereof, i-tis to'be understood "that matter herein set forth or shown in the accompanying drawing is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. In a governor mechanism of the character described having a stationary brake member mounted adjustably in cooperative relation to a rotatable shaft and an axially and rotatably movable brake member on said shaft cooperative with said stationary member, brake operatingmeans comprising a pair of weights mounted in balanced relation upon opposite sides of said shaft and pivoted to be swung by centrifugal force about a pivot mounted in and extending transversely through said shaft in axially normal relation therewith, resilient means operatively connecting said weights and adapted partially to counteract centrifugal force and limit the swing of said weights, and positive cooperative means associated with said weight pivot and said movable brake member for imparting rotation to said movable member.

2. In a centrifugal governor of the character described comprising a rotatable shaft, a brake member rotatably and slidably mounted on said shaft, and a pair of centrifugally actuated weights carried respectively upon opposite sides of said shaft for imparting rotation and axial movement to said brake member, a pivot carried by said shaft in intersecting normal relation to the axis of said shaft, a pair of supporting arms for each of said pair of weights movably mounted upon said pivot astride said shaft, one member of each pair of arms lying in contact with said shaft upon opposite sides thereof and the other member of each pair lying in contact with the said one member of the other pair, means for holding the pivot and weight arms in operative relation to said shaft, spring means connecting said weights and normally holding them in closed-in position relatively to said shaft, and resilient means tending at all times to hold said brake member in operative contact with said weight arms.

3. In a centrifugal governor of the character described comprising a rotatable shaft, a brake member rotatably and slidably mounted on said shaft, and a pair of centrifugally actuated weights carried respectively upon opposite sides of said shaft for imparting rotation and axial movement to said brake member, a pivot carried by said shaft in intersecting normal relation to the axis of said shaft, a pair of cam-faced supporting arms for each of said weights movably mounted upon said pivot astride said shaft, the respective pairs being in oppositely ofiset relation to the center of said shaft, means for holding said weight arms upon said pivot in operative relation to said shaft, and resilient means tending guinea to move said brake member into contact with said cam-faced arms and; thereby,'saidurweights into closed-in position relatively to said shaft.

4. In a centrifugal governor of the character described comprising a rotatable shaft, a brake member rotatably andslidablymounted on saidshait, and a pair of centrifugally actuated weights. carried respectively upon opposite sides of said shaft for imparting rotation and axial movement to saidbrake member, a pivot carried by said shaft in intersecting normal relation to the axis of said shaft, oam-faced arms movably supporting said weights upon said pivots in balanced relation to said shaft, spring means connecting said weights and tending to draw them into closed-in position adjacent the sides of said brake member in contact with said cam-faced weight arms.

JOHN H.

1 REFERENCES crrEn I The following referenlces are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date I 675,608 Nelson June 4, 1901 859,780 Rodesch July 9, 1907 V 962,819 Cowley June 28, 1910 2,433,885 Bossmeyer Jan. 6, 1948 

